Crankshaft damper with integral pulse ring and method

ABSTRACT

The invention comprises a crankshaft damper having an integral pulse ring. The crankshaft damper comprises an inner hub and outer pulley with an elastomeric connecting member between each. The elastomeric ring dampens a crankshaft vibration. The integral pulse ring is manufactured as part of the inner hub by flow forming a sheet metal blank.

REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. provisionalapplication serial No. 60/310,034 filed Aug. 3, 2001.

FIELD OF THE INVENTION

[0002] The invention relates to crankshaft dampers and more particularlyto crankshaft dampers having an integral pulse ring and a method ofmaking same.

BACKGROUND OF THE INVENTION

[0003] Reciprocating internal combustion engines generally comprise,among other things, a crankshaft for power output. Engine accessorycomponents are driven by a belt connected to a pulley on one end of thecrankshaft. During operation the crankshaft vibrates in various modesdue to the reciprocating nature of the engine. Such vibration canadversely affect operation and long-term reliability. Consequently,viscoelastic dampers may be incorporated into crankshaft pulleys to dampcrankshaft vibration. Such combinations of pulley and viscoelasticdamper are simply referred to as “crankshaft dampers”. The crankshaftdamper generally comprises an inner hub and an outer pulley. The outerpulley is generally attached to the inner hub by a viscoelasticelastomeric ring.

[0004] In certain applications crankshaft dampers may include a pulsering or timing gear for engine ignition timing. The pulse ring rotatesin front of a sensor attached to the engine. The pulse ring generallyincludes a gap as a reference point, for example, to indicate TDC forcylinder one. The pulse ring is generally attached to the crankshaftdamper outer pulley. However, due to the vibration and relative motion,albeit small, of the hub to the pulley made possible by the elastomerring, accurately detecting the pulse ring location on the outer pulleycan be adversely affected. Consequently, for very precise applications,the pulse ring is attached to the inner hub, which is then rigidlyassembled on the crankshaft. However, prior art pulse rings comprise aseparate part that must be press fit, welded or otherwise attached usingother means to the inner hub.

[0005] Representative of the art is U.S. Pat. No. 5,203,223 (1993) toHimmeroeder that discloses a cold-former gear made from a singlecircular sheet of sheet metal.

[0006] Also representative of the art is U.S. Pat. No. 5,966,996 (1999)to Hamaekers that discloses an annular machine part comprising at leasttwo metal machine elements which are separated from each other by aviscoelastic layer. A separately produced extension piece projects fromone of the machine elements.

[0007] Also representative of the art is a crankshaft dampermanufactured by Freudenberg NOK having an inner hub and an outer ringjoined by an elastomeric ring. A pulse ring is press fit into the innerhub.

[0008] The prior art pulse rings are not-integral to the inner hubmaking them subject to detaching from the inner hub or damper.

[0009] What is needed is a crankshaft damper having an integral pulsering. What is needed is a crankshaft damper having an integral pulsering whereby the integral pulse ring is flow formed on an inner hub. Thepresent invention meets these needs.

SUMMARY OF THE INVENTION

[0010] It is a feature of the invention to provide a crankshaft damperhaving an integral pulse ring.

[0011] Another feature of the invention is to provide a crankshaftdamper having an integral pulse ring whereby the integral pulse ring isflow formed on an inner hub.

[0012] Other aspects of the invention will be pointed out or madeobvious by the following description of the invention and theaccompanying drawings.

[0013] The invention comprises an improved crankshaft damper having anintegral pulse ring. The crankshaft damper comprises an inner hub andouter pulley with an elastomeric connecting member between each. Theelastomeric member dampens a crankshaft vibration. The integral pulsering is manufactured as part of the inner hub by flow forming a sheetmetal blank.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings that are incorporated in and form apart of the specification illustrate preferred embodiments of thepresent invention, and together with a description, serve to explain theprinciples of the invention.

[0015]FIG. 1 is a cross-sectional view of the inventive crankshaftdamper.

[0016]FIG. 2 is a cross-sectional view of the inventive crankshaftdamper.

[0017]FIG. 3 is a front elevation view of the inventive crankshaftdamper.

[0018]FIGS. 4a, 4 b, 4 c, 4 d, 4 e, 4 f, 4 g are half cross-sectionalviews of a fabrication sequence.

[0019]FIGS. 5a, 5 b, 5 c, 5 d are half cross-sectional views of afabrication process.

[0020]FIG. 6 is a cross-sectional perspective view of the inner hub ofthe inventive damper.

[0021]FIG. 7a, 7 b, 7 c are cross-sectional views of the formation of ahub having a closed bore.

[0022]FIGS. 8a, 8 b, 8 c, 8 d, 8 e, 8 f, 8 g, 8 h, 8 i, 8 j are halfcross-sectional views of a fabrication sequence.

[0023]FIGS. 9a, 9 b, 9 c are half cross-sectional views of a fabricationprocess.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] The improvements of the inventive damper over the prior art aremany fold. The inventive damper allows much better timing accuracy to beachieved using the flow formed integral pulse ring as opposed to twoseparate parts as in the prior art. This significantly improves theaccuracy of the location of the pulse ring relative to the inner hub andthe pulley, both radially and laterally. This in turn improves theaccuracy of determining the position of the crankshaft for timingpurposes. Further, a more accurate gap dimension for containing theconnecting member is achieved between the ring and the pulley; as isbetter run out and concentricity. The inventive damper is also strongerthan the prior art construction. The inventive pulse ring is not subjectto detaching from the inner hub as in the prior art. With respect tofabrication, the inventive damper has fewer pieces requiring fewerassembly operations as compared to the prior art. Since the inventivedamper is flow formed the quality of the pulse ring is superior to thatof the manufactured pulse rings of the prior art.

[0025]FIG. 1 is a cross-sectional view of the inventive crankshaftdamper. The inventive crankshaft damper 100 is formed of metallicmaterial and comprises an inner member or hub 110 and outer member orring 120. Flexible connecting member 14 is fit between inner hub 110 andouter ring 120. In the preferred embodiment connecting member 14comprises a viscoelastic, elastomeric ring. Elastomeric ring 14 maycomprise, but be not limited to SBR, NBR, HNBR, EPDM, VAMAC, EVM andblends of the above.

[0026] Inner hub 110 comprises center hub 10. Center hub 10 comprisesbore 11 into which a crankshaft (not shown) is inserted. Inner hub 110also comprises web 12 to which interface ring 13 is formed. Line C-C isa centerline of the inventive damper as well as an axis of rotation. C-Caligns with a crankshaft centerline (not shown). C-C is also depicted inFIG. 2, FIGS. 4a-4 g, FIGS. 5a-5 d, FIGS. 8a-8 j and FIGS. 9a-9 c.

[0027] Pulse ring 17 is flow formed integrally with inner hub 110. Pulsering 17 extends substantially normal to an axis of rotation, C-C, of theinventive damper. An outer perimeter of pulse ring 17 comprises tabs orteeth 18. Teeth 18 extend radially from pulse ring 17. In operation,when the inventive damper is rotating on a crankshaft, teeth 18 aredetected by a sensor on an engine (not shown) for engine ignitiontiming.

[0028] Outer ring 120 comprises pulley 15. Pulley 15 is engaged withinner hub 110 by connecting member 14. In this embodiment outer ring 120is cast in a fashion known in the art. Outer interface ring surface 19,connecting member 14 and pulley inner surface 20 may have any suitableprofile, including that of an arcuate curve. Surface 19 and surface 20and member 14 may have other cooperating profiles as may be required bya user, including nodes and undulations. Surface 19 and surface 20otherwise have a substantially cylindrical form into which the notedprofiles are incorporated, see FIG. 3. Pulley 15 comprises a beltbearing surface having a multi-ribbed profile 16. The belt bearingsurface 16 may also have a toothed profile or a v-belt profile.

[0029] Plane P1 of web 12 is offset distance D1 from a belt bearingsurface plane P2-P2. This cantilever construction allows belt bearingsurface 16 to be recessed toward an engine thereby requiring lessclearance space in front of an engine.

[0030]FIG. 2 is a cross-sectional view of the inventive crankshaftdamper. Outer ring 130 comprising pulley 25 is spun or flow formed inthis embodiment in a fashion known in the art. Belt bearing surface 26has a multi-ribbed profile and is spun or flow formed into the pulley 25outer surface. The belt bearing surface 16 may also have a toothedprofile or a v-belt profile. Surface 30 cooperates with surface 19. Allother components are as described in FIG. 1.

[0031] Plane P1 of web 12 is offset distance D1 from a belt bearingsurface plane P2-P2. This cantilever construction allows belt bearingsurface 26 to be recessed toward an engine thereby requiring lessclearance space in front of an engine.

[0032]FIG. 3 is a front elevation view of the inventive crankshaftdamper. Teeth 18 extend about a perimeter of pulse ring 17. Outer ring120 is engaged with inner hub 110 by member 14. A timing means or gap 30in teeth 18 comprises a timing reference point between teeth 18 to bedetected by a sensor (not shown). Gap 30 may comprise any form ofdiscontinuity in teeth 18 that may be detected by a sensor. Teeth 18extend beyond an outer perimeter of profile 16.

[0033]FIGS. 4a, 4 b, 4 c, 4 d, 4 e, 4 f, 4 g are half cross-sectionalviews along axis C-C of a fabrication sequence. FIG. 4a depicts ablanking step. Sheet metal blank 1000 is stamped or cut in a knownfashion into a circular form. It is then mounted in a rotating mandrel.

[0034]FIG. 4b shows the closed bore center hub 10 as spun by processesknow in the art, including the method disclosed in U.S. Pat. No.5,987,952 to Kutzscher et al. incorporated herein by reference in itsentirety. FIG. 7a, 7 b, 7 c are cross-sectional views of the formationof a hub having a closed or blind bore. Referring to FIG. 7a, the hub isformed by spinning annular disc or blank 1000 supported by rotatingmandrel M. Roller RA having forming profile RA1 is moved radiallyinwardly in direction SR against a side 1010 of blank 1000, therebydisplacing a portion 64 of blank 1000 inwardly against a mandrel to formhub 10. Roller RB holds an outer perimeter of blank 1000 in placeagainst mandrel M during the forming process. Roller RB rolls on blank1000 and mandrel M as mandrel M rotates. FIG. 7b shows the furtherprogression of roller RA in direction SR2 thereby moving portion 64inward toward mandrel post MP. FIG. 7c shows the fully formed hub 10. InFIG. 7c, roller RC is shown applying the final shape top hub 10. RollerRC has a different forming profile RC1 than that of roller RA in orderto properly form the cylindrical shape of finished hub 10.

[0035] Bore 11 is a blind or closed bore in that diameter D1 is greaterthan diameter D2, see FIG. 1. A fastener (not shown) such as a bolt maythen be inserted through hole 11 a to fasten the inventive damper to ashaft (not shown). The inventive damper may also instead use a hub nothaving a blind bore, using a key to secure the damper to a crankshaft(not shown). The described methods of fastening the damper to a shaftare intended as examples and are not meant to limit the manner in whichthe damper may be fastened to a shaft.

[0036]FIG. 4c shows formation of the interface ring 13 and pulse ring17. This process is further described in FIGS. 5a through 5 d.

[0037]FIG. 4d shows machining performed on the formed surfaces as knownthe art. The rubber interface surface 19 is machined to a predeterminedfinish for proper engagement with the elastomeric member 14. A suitablesurface finish may also be applied by known processes, such as bypainting or coating with epoxy.

[0038]FIG. 4e shows the piercing step. Teeth 18 and web openings 27, seeFIG. 3, are formed by piercing. Piercing includes any known stampingprocess by which metal is removed from the inner hub 110 to from webopenings 27 and from the pulse ring 17 to form teeth 18. Teeth 18 mayalso be spun or flow formed in a known fashion.

[0039]FIG. 4f shows outer ring 120 engaged to interface ring 13 with theconnecting member elastomeric ring 14. In this step outer ring 120 andinner hub 110 are held in relative fixed positions. Member 14 is thenpressed between ring 120 and hub 110. Member 14 is in a somewhatcompressed state between the inner hub and outer ring, in a range ofapproximately >0% to approximately 50% compression of a thickness, inorder to facilitate engagement of member 14 with outer ring 120 andinner hub 110. An adhesive may be used in a known fashion to securemember 14 between the inner hub 110 and outer ring 120.

[0040]FIG. 4g shows a final machining step to complete the center hub 10in a fashion known in the art. This may include application of apredetermined surface finish by machining, painting or coating.

[0041]FIGS. 5a, 5 b, 5 c, 5 d are half cross-sectional views along axisC-C of a fabrication process. The form shown in FIG. 4b is furtherformed by a roller R1 having forming profile RP1 moving radially inwardin direction DR1 to form a gathered portion 1050 of blank 1000. Gatheredportion 1050 is accumulated against mandrel section M1 and M2. Gatheredportion 1050 is then split by roller R2 having rolling profile RP2moving radially inwardly in direction DR2 while portion 1050 issimultaneously spread to form lobe 1060, see FIG. 5b. Lobe 1060 iscollected against mandrel section M2. Next, lobe 1060 is stretched byroller R3 moving in direction DR3 and then in direction DR4. Roller R3having rolling profile RP3 further forms lobe 1060 into the rough shapeof the interface ring 1300 and pulse ring 1700 against mandrel sectionMR2, see FIG. 5c. An inner surface 1301 of lobe 1060 is supported by amandrel section MR2 during the stretching step in FIG. 5c. Next, finalstretch forming using roller R4 having rolling profile RP4 gives thefinal shape to interface ring 13 and pulse ring 17, including surface19, see FIG. 4d. Roller R4 moves in direction DR5 to form a flat surface1701 for pulse ring 17, thereby forming the final radially extendingmember shape of ring 17, see FIG. 5d.

[0042]FIG. 6 is a cross-sectional perspective view of the inner hub ofthe inventive damper. Inner hub 110 comprises center hub 10. Center hub10 comprises bore 11 into which a crankshaft (not shown) may beinserted. Inner hub 110 also comprises web 12 to which interface ring 13is formed. Pulse ring 17 is formed integrally with inner hub 110 asdescribed herein. An outer perimeter of pulse ring 17 comprises tabs orteeth 18. In operation, teeth 18 as well as gap 30 are detected by asensor on an engine (not shown).

[0043]FIGS. 8a, 8 b, 8 c, 8 d, 8 e, 8 f, 8 g, 8 h, 8 i, 8 j are halfcross-sectional views along axis C-C of a fabrication sequence. FIG. 8adepicts a blanking step. Sheet metal blank 2000 is stamped or cut in aknown fashion into a circular form. It is then mounted in a rotatingmandrel.

[0044]FIG. 8b shows the closed bore center hub 10 as spun by processesknow in the art, including the method disclosed in U.S. Pat. No.5,987,952 to Kutzscher et al. incorporated herein by reference in itsentirety. FIG. 7a, 7 b, 7 c are cross-sectional views of the formationof a hub having a closed or blind bore as described elsewhere herein.

[0045] Fog. 8 c shows press forming of the partially formed disc. Offset2001 is pressed by known processes into the damper web 12.

[0046]FIG. 8d, 8 e and 8 f shows formation of the interface ring 13 andpulse ring 17 and are more fully described in FIG. 9a, 9 b, and 9 c.

[0047]FIG. 8g shows machining performed on the formed surfaces as knownthe art. The rubber interface surface 19 is machined for properengagement with the elastomeric member 14. A predetermined surfacefinish may also be applied by known processes, such as by painting orcoating with epoxy.

[0048]FIG. 8h shows the piercing step. Teeth 18 and web openings 27, seeFIG. 3, are formed by piercing. Piercing includes any known stampingprocess by which metal is removed from the inner hub 110 to from webopenings 27 and from the pulse ring 17 to form teeth 18. Teeth 18 mayalso be spun formed in a known fashion.

[0049]FIG. 8i shows outer ring 120 engaged to interface ring 13 with theconnecting member elastomeric ring 14. In this step outer ring 120 andinner hub 110 are held in relative fixed positions. Member 14 is thenpressed between ring 120 and hub 110. Member 14 is in a somewhatcompressed state between the inner hub and outer ring, in a range ofapproximately >0% to approximately 50%, in order to facilitateengagement between outer ring 120 and inner hub 110. An adhesive may beused in a known fashion to secure member 14 between the inner hub 110and outer ring 120.

[0050]FIG. 8j shows a final machining step to complete the center hub 10in a fashion known in the art. This may include application of asuitable surface finish by machining or by painting.

[0051]FIGS. 9a, 9 b, 9 c are half cross-sectional views of a fabricationprocess. Damper blank 2000 shown in FIG. 8c is clamped between rotatingmandrel sections M3 and M4. The form shown in FIG. 8c is then furtherformed by roller R5 having forming profile RP5 moving substantiallyradially inward in direction DR6 to form a radius portion 2002 of blank2000. Arcuate radius portion 2002 is formed against mandrel section M4by action of roller R5. Radius portion 2002 is then stretched by rollerR5 having rolling profile RP5 moving substantially radially outwardly indirection DR7 to create a rough form of pulse ring 17. Referring to FIG.9b, roller R5 moving in direction DR8 further completes pulse ring 17and the rough shape 2003 of the interface ring 13 against mandrelsections MR3 and M4. In FIG. 9c, roller R6 with rolling profile RP6moves substantially radially inward in direction DR9 to further flattenpulse ring 17 and to give final form to interface ring 13, and inparticular surface 19, see FIG. 8g.

[0052] In this alternate embodiment offset 2001 engages interface ringat a position that is substantially centered upon and radially alignedwith a belt bearing surface, 16 and 26, see FIGS. 1, 2, 8 i and 8 j.This serves to illustrate the versatility available with this method forpositioning a belt bearing surface relative to a damper web. This inturn allows a user to design a flow formed damper to optimize use ofavailable space in an engine compartment.

[0053] Although a single form of the invention has been describedherein, it will be obvious to those skilled in the art that variationsmay be made in the construction and relation of parts without departingfrom the spirit and scope of the invention described herein.

We claim:
 1. A damper comprising: an inner member having an outersubstantially cylindrical surface; an outer member having an innersubstantially cylindrical surface; the inner member outer surface andthe outer member inner surface joined by a flexible connecting member;the inner member further comprising an integral radially extendingmember, the integral radially extending member having a plurality ofspaced tabs extending about an outer perimeter of the inner member. 2.The damper as in claim 1, wherein the inner member further comprises ahub for engaging a shaft.
 3. The damper as in claim 2, wherein the outermember further comprises a belt bearing surface having a profile.
 4. Thedamper as in claim 3, wherein the belt bearing surface comprises amulti-ribbed profile.
 5. The damper as in claim 2, wherein the hubfurther describes a bore for engaging a shaft.
 6. The damper as in claim1, wherein the flexible connecting member comprises an elastomericmaterial.
 7. The damper as in claim 1 further comprising a discontinuitysubject to detection by a sensor.
 8. The damper as in claim 7, whereinthe discontinuity comprises a gap between adjacent tabs.
 9. A method offorming a crankshaft damper comprising: forming a first ring by spinninga first annular disc supported in a rotating mandrel, moving a firstroller radially inwardly against a side of the first disc displacing aportion of the first disc inwardly against a mandrel to form a hub,pressing a second roller radially inwardly against a first annular discedge whereby a gathered portion of the first annular disc is formed,splitting the gathered portion by inward radial movement of a rollerwhile simultaneously forming a lobe from the gathered portion,stretching the lobe in a radial direction by outward radial movement ofa second roller while simultaneously supporting a portion of thegathered portion, thereby simultaneously forming a radially extendingmember substantially normal to an axis of rotation of the first ring;forming a plurality of tabs extending about a perimeter of the radiallyextending member; forming a second ring by spinning a second annulardisc supported in a rotating mandrel, moving a first roller radiallyinwardly against a second annular disc edge whereby a gathered portionof the second annular disc is formed, pressing a roller having a profileagainst the gathered material whereby a profile is formed in a secondring outer surface; and connecting the first ring to the second ring byengaging a flexible connecting member between the first ring and thesecond ring.
 10. The method as in claim 9, wherein the connecting membercomprises an elastomeric material.
 11. The method as in claim 9 furthercomprising forming a profile in the first ring outer surface and forminga profile in the second ring inner surface to cooperate with the firstring outer surface profile.
 12. The method as in claim 10, comprisingforming a multi-ribbed profile in the second ring outer surface.
 13. Themethod as in claim 9 comprising stamping to form the tabs.
 14. Themethod as in claim 9 comprising forming a gap in the tabs.